The Y chromosome, the strand of DNA that determines male sex, contained about 800 genes some 200 million years ago. Now, though, it has only 30, leading some scientists to conclude it could disappear altogether, bringing about the end of men.

That’s probably not the case, said Jennifer Hughes, a researcher with the Whitehead Institute for Biomedical Research, in Cambridge, Massachusetts. The number of genes on the chromosome have been stable for at least the past 25 million years, she and her colleagues found in a study reported in the journal Nature.

“Although the Y chromosome did suffer quite a bit over the course of evolution, it seems like what remains of it is not going anywhere,” Hughes said in a telephone interview. “The genes that remain on it have critical biological functions, and that means they are going to survive.”

Hughes and colleagues compared chromosomes of humans to a Rhesus monkey, a species that split from human ancestors 25 million years ago, and that of chimpanzees, which separated 6 million years ago.

The data led them to conclude that the Y chromosome decays quickly at first, then stabilizes and keeps genes important to continuing its existence, she said.

--Editors: Reg Gale, Angela Zimm

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To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net